Warming oceans threat

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Warming oceans are threatening the billions of people around the world who are dependent on marine ecosystems.

A UN report Frontline Observations on Climate Change and Sustainability of Large Marine Ecosystems found that climate change is robbing oceans of fish. The fish are move northwards. “Such trends have become a direct threat to food and national security for some coastal communities, and include the loss of investments and jobs related to fish processing. Increased insecurity in coastal areas only fuels tension that exists among neighbouring countries over disputed areas of oceans, islands, fish stocks, oil/gas reserves and pollution loading.”

According to University of British Columbia professor Villy Christensen, warming oceans have seen big fish like grouper and cod experiencing a 55 percent decline in last 40 years. In their place are small, oily fish such as myctophids, not the sort of fish humans are interested in catching and eating.

It’s having a massive impact. In West Africa, large populations of sardines are moving away from traditional fishing grounds. This represents a major loss in protein supplies for the region. In northwest Africa, stocks of sardines and mackerel are moving from traditional fishing areas in Senegal northward towards cooler waters off the coast of Mauritania. In southwest Africa, sardines and mackerel populations are moving southward from Namibia, towards the cooler waters and onto the Agulhas banks area of South Africa. In Asia, the increased intensity of monsoon rains in the Bay of Bengal is lowering the salinity of surface waters. Lower salinity is inhibiting nutrient replenishment of surface waters, thereby lowering natural productivity, and fish populations. As a result, food security for millions of people in coastal communities is at risk. US research has found that warming oceans are largely a man-made phenomenon, caused by climate change.

The other problem is that as oceans warm, the water actually expands and takes up more space. As a basic physics phenomenon, it’s called thermal expansion. This means that as water temperatures rise, sea levels will also rise. Scientists say that a one-metre increase in sea levels could have as great an impact on coastlines as fast onset disasters such as tsunamis.

According to National Geographic, the organism most vulnerable to warming oceans are coral. But warming oceans can also destroy krill, a crucial part of the marine food chain. That will affect the life cycle of krill eaters like penguins and seals which will in turn have an impact on higher predators. National Geographic reports: “Warmer sea temperatures are also associated with the spread of invasive species and marine diseases. The evolution of a stable marine habitat is dependent upon myriad factors, including water temperature. If an ecosystem becomes warmer, it can create an opportunity where outside species or bacteria can suddenly thrive where they were once excluded. This can lead to forced migrations and even species extinctions.”

Australian scientists warn that warmer oceans oceans can’t absorb CO2. As result, greenhouse gases will remain in the atmosphere, further warming the planet.

Of course, the obvious way to address it is to tackle climate change. But even if we succeeded there – and that’s by no means certain – because the gases already released would take decades to dissipate. On the other hand, doing nothing and gambling that ocean warming is cyclical, that atmospheric warming in the last century is an aberration and not a consequence of greenhouse gas emissions, is too risky when we’re already seeing the impact on marine life.